Semiconductor Device With An Interlocking Wire Bond

ABSTRACT

In one embodiment, a semiconductor device having a die attach pad, an interlocking wire bond, a semiconductor die and an adhesive material is disclosed. The adhesive material may be configured to adjoin the semiconductor die and the die attach pad. A portion of the interlocking wire bond may be submerged within the adhesive material. In another embodiment, a device having a semiconductor die, a die attach glue and a die attach pad is disclosed. The device may comprise an interlock bonding structure submerged within the adhesive material. In yet another embodiment, a light-emitting device comprising an interlock structure is disclosed.

BACKGROUND

Semiconductor devices may be implemented using various packagingtechnologies such as a plastic leaded chip carrier (herein after PLCC)package, a ball grid array package (herein after BGA), a pin grid arraypackage (herein after PGA), a quad flat pack (herein after QFP), aprinted circuit board (herein after PCB) package and so on. Certainpackages, for example PLCC packages in light-emitting devices, maycomprise a lead frame over a molded polymer material such asPolyphthalamide (herein after PPA), Polyamide or Epoxy resin encapsulantlike MG 97. For surface mount type, leads extending from the lead framemay be bent so that the semiconductor devices can be soldered on asubstrate without through-holes. One of the most popular semiconductordevices may be opto-electronic device. One characteristic ofopto-electronic devices may be the feature of having a light source dieor a radiation source die. Example of opto-electronic devices may beopto-couplers, light emitting devices, proximity sensors, encoders andother similar devices having a radiation source.

One of the reasons why many semiconductor devices fail reliability testmay be due to delamination of encapsulant or epoxy material surroundinga semiconductor die. After going through hundreds or thousands oftemperature cycles, some semiconductor dies may be lifted-up from thedie attach pad, causing an open circuit. One explanation of the failuremay be due to delamination of the epoxy material. Further, the failurerate may be higher for industrial or automotive use semiconductordevices, which may be required to operate at wide range of temperatures.Additionally, the failure rate for opto-electronic devices may berelatively higher due to the use of substantially transparent epoxy asencapsulant body. Most epoxy used in opto-electronic devices may besusceptible to delamination especially. The result may be that theentire transparent encapsulant body, as well as the light source die maybe lifted up from the die attach pad more easily, compared to non-opticstypes of devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments by way of examples, not by way of limitation,are illustrated in the drawings. Throughout the description anddrawings, similar reference numbers may be used to identify similarelements. The drawings may be for illustrative purpose to assistunderstanding and may not be drawn per actual scale. For example, theinterlocking wire bond of each embodiment may be drawn relatively largerthan actual scale to enhance understanding.

FIG. 1 shows an illustrative block diagram of a semiconductor devicehaving an interlocking wire bond;

FIG. 2A illustrates a cross-sectional view of a semiconductor devicehaving an interlocking wire bond;

FIG. 2B illustrates a top view of the semiconductor device shown in FIG.2A;

FIG. 3A illustrates a cross-sectional view of an alternativesemiconductor device having an interlocking wire bond;

FIG. 3B illustrates a top view of the semiconductor device shown in FIG.3A;

FIG. 4A illustrates a cross-sectional view of a semiconductor devicehaving an interlocking bond ball;

FIG. 4B illustrates a top view of the semiconductor device shown in FIG.4A;

FIG. 5A illustrates a cross-sectional view of a semiconductor devicehaving an interlocking bond wire within a groove;

FIG. 5B illustrates a top view of the semiconductor device shown in FIG.5A;

FIG. 6A illustrates a cross-sectional view of a semiconductor devicehaving an interlocking bond wire within a trench;

FIG. 6B illustrates a top view of the semiconductor device shown in FIG.6A;

FIG. 6C illustrates a perspective cut-away view of the die attach padand the semiconductor die of the semiconductor device shown in FIG. 6A;

FIG. 7 illustrates a cross-sectional view of a device having a pluralityof semiconductor dies;

FIG. 8A illustrates a light-emitting device;

FIG. 8B illustrates a manufacturing process step of the light-emittingdevice shown in FIG. 8A;

FIG. 9A illustrates a block diagram of a lighting system;

FIG. 9B illustrates a block diagram of an opto-electronic system;

FIG. 10A illustrates a method for providing a mechanical interlockbetween a die attach pad of a lead frame and a semiconductor die; and

FIGS. 10B-10D illustrate various alternative steps for the method shownin FIG. 10A.

DETAILED DESCRIPTION

FIG. 1 shows an illustrative block diagram of a semiconductor device100. The semiconductor device 100 may be an electronic device. Examplesof a semiconductor device may be an encoder, an application specificintegrated circuit (also referred as “ASIC”), camera modules,opto-electronic devices such as opto-couplers, encoders, proximitysensors and any other similar devices having a die in a packaging. Thesemiconductor device 100 may comprise a die attach pad 110, an interlockbonding structure 120, an adhesive material 140, a semiconductor die 150and a body 160. The die attach pad 110 may comprise a major surface 115for receiving the semiconductor die 150. The die attach pad 110 may beportion of a lead frame (not shown) encapsulated at least partiallywithin the body 160. “Lead frame” (not shown) as used herein inreference to the semiconductor devices 100, refers to a structurecapable of electrically connecting the semiconductor die 150 to anexternal power source or an external circuit (not shown). In PLCCpackages, the lead frames may comprise a plurality of leads. Thesemiconductor device 100 in a PLCC package may comprise a plurality ofleads encapsulated partially within a plastic body 160. One of the leads(not shown) may comprise the die attach pad 110 characterized by awidened portion to receive the semiconductor die 150.

In the embodiment shown in FIG. 1, the die attach pad 110 may be made ofelectrically and thermally conductive material, such as steel, copper,metal or a metal alloy, a metal compound or other similar materials. Thedie attach pad 110 may be formed using any stamping, cutting, etching orother similar process. The semiconductor die 150 may be attached on thedie attach pad 110 via the adhesive material 140. The adhesive material140 may be configured to adjoin the semiconductor die 150 and the dieattach pad 110. For example, the adhesive material 140 may be applied tothe major surface 115 of the die attach pad 110 first before thesemiconductor die 150 is mounted to the die attach pad 110. The adhesivematerial 140 may be referred as “die attach glue” or “DA glue”. Theadhesive material 140 may comprise epoxy, silicone or other similarmaterial that may be adhesive to adjoin the semiconductor die 150 to thedie attach pad 110. The adhesive material 140 may comprise electricallyconductive material. The adhesive material 140 may be in a substantiallyliquid form during the die attach process but may be subsequently curedinto solid form. The adhesive material 140 may be opaque but in anotherembodiment, the adhesive material 140 may be substantially transparent.

The interlock bonding structure 120 may be a wire bond, a bond ball orany other structure configured to electrically connect at least oneportion of the semiconductor die 150 to an external circuit or anexternal power source. However, the interlock bonding structure 120 maybe at least differentiated from a wire bond in that the interlockbonding structure 120 may not be physically coupled to the semiconductordie 150 for an electrical connection. Instead, the interlock bondingstructure 120 may be configured to establish a mechanical interlock. Forexample, in the embodiment shown in FIG. 1, the interlock bondingstructure 120 may be distanced away from the semiconductor die 150.Specifically, the interlock bonding structure 120 may be configured toprovide a mechanical interlock with the adhesive material 140. As theinterlock bonding structure 120 may be attached to the die attach pad110 of the lead frame (not shown) or to one of the lead frame directly,the mechanical interlock established through the interlock bondingstructure 120 may be configured to provide a mechanical interlockbetween the adhesive material 140 and the die attach pad 110, or one ofthe lead frame. The interlock bonding structure 120 implemented using awire bond may be referred hereinafter as interlocking wire bond 120whereas the interlock bonding structure 120 implemented using a bondball may be referred hereinafter as interlocking bond ball 120. However,when one of the interlocking bond ball 120 or the interlocking wire bond120 is referred, all types of interlock bonding structure 120 should beincluded into consideration.

The interlock bonding structure 120 may be sandwiched between thesemiconductor die 150 and the major surface 115 of the die attach pad110. Alternatively, the interlock bonding structure 120 may be disposedon the major surface 115 of the die attach pad 110 adjacent to thesemiconductor die 150 without being sandwiched in between.

Optionally, the interlock bonding structure 120 may comprise a first end128 and a second end 129 configured to be attached on either on themajor surface 115 of the die attach pad 110 or a portion of a lead (notshown). A middle portion 127 of the interlock bonding structure 120 mayengage substantially the adhesive material 140 so as to establish themechanical interlock between the interlocking boding structure 120 andthe adhesive material 140. The arrangement shown in FIG. 1 may improvethe interlock between the adhesive material 140 and the die attach pad110. The adhesion force between the first end 128 and the second end 129of the interlock bonding structure 120 may be higher than the adhesionforce between the adhesive material 140 and the die attach pad 110. Withthe arrangement shown in FIG. 1, the adhesion force between the adhesivematerial 140 and the die attach pad 110 may be supplemented by themechanical interlock between the adhesive material 140 and theinterlocking structure 120 in addition to the adhesive force between thedie attach pad 110 and the adhesive material 140 directly. As a result,reliability performance may improve.

In one manufacturing process, the interlock bonding structure 120 may beformed first prior to the step of applying the adhesive material 140 tothe die attach pad 110. As a result, a thin layer of the adhesivematerial 140 may be formed between the semiconductor die 150 and the dieattach pad 110. The thin layer of the adhesive material 140 sandwichedbetween the semiconductor die 150 and the interlock bonding structure120 of the die attach pad 110 may be less than fifty microns. Thisarrangement may reduce packaging height. Optionally, the semiconductordie 150 may be attached directly to the die attach pad 110 adjacent tothe interlock bonding structure 120 in order to reduce packaging height.

The adhesive material 140 may be configured to cover at least partiallythe interlock bonding structure 120 as shown in FIG. 1. In anotherembodiment, the adhesive material 140 may cover entirely the interlockbonding structure 120 including the first end 128 and the second end 129of the interlock bonding structure 120. The adhesive material 140 may beapplied to a lower portion of the semiconductor die 150. As illustratedin FIG. 1, the adhesive material 140 may be configured to surround thelower portion of the semiconductor die 150. In one embodiment where thesemiconductor die 150 comprises a light source, the adhesive material140 may be substantially transparent. However, the adhesive material 140may also be a substantially opaque material. Therefore, having theadhesive material 140 confined to lower portion of the semiconductor die150 may expose substantial portion of the semiconductor die 150 so asnot to substantially block light emission.

In another embodiment where the semiconductor die 150 may comprise aphoto-detector on a top surface 155 of the semiconductor die 150, theadhesive material 140 may be distanced away from the top surface 155 ofthe semiconductor die 150 such that light may be transmitted to thesemiconductor die 150 without being blocked by the adhesive material140. In yet another embodiment where the semiconductor die 150 is alight-emitting die, the adhesive material 140 that may be opaque may becovering less than 20% of the height of the semiconductor die 150 so asnot to obstruct the light emission.

FIG. 2A illustrates a cross-sectional view of a semiconductor device200. The semiconductor device 200 may comprise a plurality of leads 212,214, a die attach pad 210, a die attach surface 216, a semiconductor die250, an interlocking wire bond 220 an additional interlocking wire bond222 and an encapsulant body 260 having a lower portion 262 and an upperportion 264. Optionally, the semiconductor device 200 may comprise awire bond 225. A top view of the semiconductor device 200 may be shownin FIG. 2B. The top view of the semiconductor device 200 shown in FIG.2B may be at a stage prior to formation of the encapsulant body 260 soas to expose the semiconductor die 250 and the interlocking wire bond220 for illustration purpose.

Referring to FIG. 2A and FIG. 2B, one of the leads 214 may comprise thedie attach pad 210 having a major surface 215. The major surface 215 mayform a portion of the die attach surface 216. The semiconductor die 250may be mounted on the major surface 215 of the die attach pad 210. Themajor surface 215 of the die attach pad 210 may be disposed within a dieattach surface 216 of the semiconductor device 200. The die attachsurface 216 may be configured to receive the semiconductor die 250. Thedie attach surface 216 may comprise the major surface 215 and a surfaceof lower portion 262 of the encapsulant body 260.

The semiconductor die 250 may be mounted on the die attach pad 210 suchthat a bottom surface of the semiconductor die 250 may engage the dieattach pad 210. An adhesive material 240 may be configured to adjoin thesemiconductor die 250 and the die attach pad 210. The adhesive material240 may comprises a die attach glue 240 that is electrically conductive.Generally, the adhesive material 240 may be applied to the die attachpad 210 prior to mounting the semiconductor die 250 on the die attachpad 210. Thus, the adhesive material 240 may be formed between thesemiconductor die 250 and the die attach pad 210.

The plurality of leads 212, 214 may be a mean for coupling thesemiconductor die 250 to an external circuit or to an external powersource (not shown). The semiconductor die 250 may be coupled to the lead212 through a bond wire 225 in addition to the electrical contactbetween the lead 214 and the semiconductor die 250. The plurality ofleads 212, 214 may be a portion of a lead frame or a portion ofconductive traces on a printed circuit board.

The encapsulant body 260 may comprise the lower portion 262 and theupper portion 264 formed using a lower mold and an upper moldrespectively. The term “body” 260 as used herein in reference to acomponent of a semiconductor device 200 may refer to a respectiveprimary structure, which provides structural support for othercomponents of the semiconductor device 200. In FIG. 2A, the encapsulantbody 260 may be epoxy, silicone or other encapsulant formedencapsulating or surrounding the plurality of leads 212, 214 and thesemiconductor die 250 using an injection molding process or othersimilar processes. In another embodiment, the body 260 may be asubstrate such as a PCB. The encapsulant body 260 may be an integralsingle piece structure formed using an opaque material such as PPA,polyamide, epoxy resin, plastic and other similar materials. In yetanother embodiment where the semiconductor device 200 comprises a lightemitting die 250, the upper portion 264 of the encapsulant body 260 maybe substantially transparent.

As shown in FIG. 2A, the interlocking wire bond 220 may be disposed onthe major surface 215 of the die attach pad 210. The interlocking wirebond 220 may be made from metallic material similar to the wire bond225. Unlike wire bond 225 that may be attached to a portion of thesemiconductor die 250 for electrical connection, the interlocking wirebond 220 may be attached on the die attach pad 210 without establishingelectrical connection with the semiconductor die 250. For example, theinterlocking wire bond 220 may comprise a first end and a second endattached on the die attach pad 210. Both of the first end and the secondend of the interlocking wire bond 220 may be attached on the die attachpad 210 or in contact with one portion of the plurality of leads 212,214. The wire bond 225 on the other hand may have a least the first endand the second end being attached on the semiconductor die 250. In theembodiment shown in FIG. 2A, the interlocking wire bond 220 may becompletely distanced away from the semiconductor die 250. In anotherembodiment, a center portion of the interlocking wire bond 220 may beconfigured to engage the semiconductor die 250 while the first end andthe second end of the interlocking wire bond 220 may remain distancedaway from the semiconductor die 250.

In the embodiment shown in FIG. 2A, a center portion of the interlockingwire bond 220 may be encapsulated within the adhesive material 240. Thefirst end and the second end of the interlocking wire bond 220 may bedistanced away from the adhesive material 240. By having the first endand the second end of the interlocking wire bond 220 being disposedoutside the adhesive material 240, delamination of the adhesive material240, if happen, would not assert a force on the first end and the secondend of the interlocking wire bond 220. In addition, the interlockingwire bond 220 may be made from metallic material that may be resilientand may be able to absorb the force arises from the delamination.

Referring to FIG. 2A, the semiconductor die 250 may have a height (H)measuring from the major surface 215 of the die attach pad 210. Theinterlocking wire bond 220 may be disposed below half of the height (H)measuring from the major surface 215 of the die attach pad 210. Forexample, the interlocking wire bond 220 may have a height (h) measuringfrom the major surface 215 of the die attach pad 210. The ratio of theheight (h) and the height (H) of the semiconductor die 250 may beapproximately less than half. In another embodiment, the interlockingwire bond 220 may be disposed below a quarter of the height (H)measuring from the major surface 215 of the die attach pad 210. Withthis arrangement, the overall size may be compact and may improvereliability result. In addition, if the semiconductor die 250 is alight-emitting die, the arrangement may prevent the interlocking wirebond 220 from blocking light emission. For optical semiconductor dies250, this arrangement may prevent obstruction of light emission.

The semiconductor device 200 may further comprise an additionalinterlocking wire bond 222 as shown in a top view of the semiconductordevice 200 shown in FIG. 2B. The interlocking wire bond 220, theadditional interlocking wire bond 222 and the die attach pad 210 may beelectrically interconnected. The additional interlocking wire bond 220may comprise a first end and a second end that may be distanced awayfrom the adhesive material 240. A shown in FIG. 2B, the first end of theinterlocking wire bond 220 and the first end of the additionalinterlocking wire bond 222 may be attached on the die attach pad 210side-by-side. Similarly, the second end of the interlocking wire bond220 and the second end of the additional interlocking wire bond 222 maybe attached on the die attach pad 210 side-by-side. As a result, theinterlocking wire bond 220 and the additional interlocking wire bond 222may be arranged substantially in parallel.

The interlocking wire bond 220 and the additional interlocking wire bond222 may be attached on the die attach pad 210 such that thesemiconductor die 250 is surrounded by the first end of the interlockingwire bond 220, the second end of the interlocking wire bond 220, thefirst end of the additional interlocking wire bond 222 and the secondend of the additional interlocking wire bond 222 on the die attach pad210. Hence, as can be seen in FIG. 2B, the interlocking wire bond 220and the additional interlocking wire bond 222 may be arrangedinterposing the semiconductor die 250 on the major surface 215 of thedie attach pad 210. This arrangement may further strengthen themechanical interlock between adhesive material 240 and the die attachpad 210 by using the interlocking wire bond 220 and the additionalinterlocking wire bond 222.

FIG. 3A illustrates a cross-sectional view of a semiconductor device300. The semiconductor device 300 may comprise a plurality of leads 312,314, a die attach pad 310, a die attach surface 316, a semiconductor die350, an interlocking wire bond 320, additional interlocking wire bond322 and an encapsulant body 360. The semiconductor die 350 may bedisposed on a major surface 315 of the die attach pad 310. The majorsurface 315 of the die attach pad 310 may form a portion of the dieattach surface 316. The die attach surface 316 may be a surface of thesemiconductor device 300 configured to receive the semiconductor die350. Optionally, the semiconductor device 300 may further comprise awire bond 325. FIG. 3B illustrates a top view of the semiconductordevice 300 shown in FIG. 3A without the encapsulant body 360 toillustrate inner portions of the semiconductor device 300 which may beotherwise covered by the encapsulant body 360.

The semiconductor device 300 may be substantially similar to thesemiconductor device 200 but may differ at least in that at least acenter portion of the interlocking wire bond 320 and the additionalinterlocking wire bond 322 may be sandwiched between the semiconductordie 350 and the die attach pad 310. Specifically, as shown in FIG. 3Aand FIG. 3B the semiconductor die 350 and the die attach pad 310 mayinterpose at least a center portion of the interlocking wire bond 320and at least a center portion of the additional interlocking wire bond322. With this arrangement, mini mum area of the die attach pad 310 maybe used.

Each of the interlocking wire bond 320 and the additional interlockingwire bond 322 may have a first end attached to the die attach pad 310respectively. In addition, each of the interlocking wire bond 320 andthe additional interlocking wire bond 322 may have a second end attachedto an additional wire bond pad 311 of a lead 314. The interlocking wirebond 320 and the additional interlocking wire bond 322 may be configuredto electrically connect the die attach pad 310 and the lead 314. Thisarrangement may impose less stress on the lead 314 as compared to theembodiment shown in FIG. 2A.

FIG. 4A illustrates a cross-sectional view of a semiconductor device400. The semiconductor device 400 may comprise a plurality of leads 412,414, a die attach pad 410 formed by a portion of a lead 414, asemiconductor die 450, a die attach surface 416, an interlock bondingstructure 420, additional interlock bonding structures 421, 422 and anencapsulant body 460. The semiconductor die 450 may be disposed on amajor surface 415 of the die attach pad 410. The major surface 415 ofthe die attach pad 410 may form a portion of the die attach surface 416.The die attach surface 416 may be a surface of the semiconductor device400 configured to receive the semiconductor die 450. The plurality ofleads 412, 414 may be a portion of a lead frame (not shown). Optionally,the semiconductor device 400 may further comprise a wire bond 325 asshown in FIG. 3A or bond balls 426, 427 to electrically connect thesemiconductor die 450 to an external circuit (not shown). FIG. 4Billustrates a top view of the sem iconductor device 400 shown in FIG. 4Awithout the encapsulant body 460 to illustrate inner portions of thesemiconductor device 400 which may be otherwise covered by theencapsulant body 460.

The semiconductor device 400 may be substantially similar to thesemiconductor device 200, but may differ at least in that thesemiconductor device 400 may comprise an interlock bonding structure 420that may be completely surrounded by or completely submerged within theadhesive material 440 as shown in FIG. 4A. In the embodiment shown inFIG. 4A, the adhesive material 440 may be a die attach glue 440 whereasthe interlock bonding structure 420 may be an interlocking bond ball420.

The interlocking bond ball 420 and the additional interlocking bondballs 421,422 may be substantially similar to the bond balls 426, 427for electrically connecting a portion of the semiconductor die 450 to anexternal circuit (not shown), but may differ at least in that theinterlocking bond ball 420 and the additional interlocking bond balls421,422 may be connected only to a portion of a lead frame, such as thedie attach pad 410 as shown in FIG. 4A and FIG. 4B, without having anydirect contact with the semiconductor die 450. In other words, theinterlocking bond ball 420 and the additional interlocking bond balls421,422 may be characterized by the feature that the interlocking bondball 420 and the additional interlocking bond balls 421,422 may beattached on a portion of a lead frame, such as the die attach pad 410.

As shown in FIG. 4A and FIG. 4B, the interlocking bond ball 420 and theadditional interlocking bond balls 421,422 may be arranged adjacent tothe semiconductor die 450 on the major surface 415 of the die attach pad410. The semiconductor die 450 may be arranged on the bond balls426-427. In another embodiment, a center portion of the semiconductordie 450 may be mounted directly on the die attach pad 410 whereas aperipheral portion of the semiconductor die 450 may be mounted on thebond balls 426-427.

FIG. 5A illustrates a cross-sectional view of a semiconductor device500. The semiconductor device 500 may comprise a plurality of leads 512,514, a die attach pad 510 formed by a portion of the lead 514, asemiconductor die 550, an interlock bonding structure 520, a wire bond525 and an encapsulant body 560. The semiconductor die 550 may bedisposed on a major surface 515 of the die attach pad 510. The majorsurface 515 of the die attach pad 510 may form a portion of the dieattach surface 516. The die attach surface 516 may be a surface of thesemiconductor device 500 configured to receive the semiconductor die550. The plurality of leads 512, 514 may be a portion of a lead frame(not shown). FIG. 5B illustrates a top view of the semiconductor device500 shown in FIG. SA without the encapsulant body 560 to illustrateinner portions of the semiconductor dev ice 500 which may be otherwisecovered by the encapsulant body 560.

The semiconductor device 500 may be substantially similar to thesemiconductor device 200, but may differ at least in that the die attachpad 510 of the semiconductor device 500 may comprise a groove 517 forreceiving the interlock bonding structure 520. The interlock bondingstructure 520 may be disposed within the groove 517. As shown in FIG. 5Aand FIG. 5B, the interlock bonding structure 520 may be completelysurrounded by or completely submerged within the adhesive material 540.Specifically, the interlock bonding structure 520 shown in theembodiment in FIG. 5A and FIG. 5B may be an interlocking wire bond 520having first and second ends submerged within the adhesive material 540.Optionally, the first and second ends of the interlocking wire bond 520may be disposed within the groove 517. The arrangement within the groove517 may reduce packaging height.

In another embodiment, the interlocking wire bond 520 may be disposed atleast partially within the groove 517. For example, one end of theinterlocking wire bond 520 may be attached on a surface within thegroove 517 whereas another end of the interlocking wire bond 520 may bedisposed outside the groove 517. However, both ends of the interlockingwire bond 520 may be submerged within the adhesive material 540. Thisarrangement may have high reliability performance compared to theembodiment shown in FIG. 5A for semiconductor devices 500 with smallersemiconductor dies 550. For semiconductor devices 500 with largersemiconductor dies 550, the arrangement shown in the embodiment in FIG.SA may be have more superior reliability performance.

FIG. 6A illustrates a cross-sectional view of a semiconductor device600. The semiconductor device 600 may comprise a plurality of leads 612,614, a die attach surface 616, a die attach pad 610 formed by a portionof the lead 614, a semiconductor die 650, an interlock bonding structure620, a wire bond 625 and an encapsulant body 660. The semiconductor die650 may be disposed on a major surface 615 of the die attach pad 610.The major surface 615 of the die attach pad 610 may form a portion ofthe die attach surface 616. The die attach surface 616 may be a surfaceof the semiconductor device 600 configured to receive the semiconductordie 650. The plurality of leads 612, 614 may be a portion of a leadframe (not shown). FIG. 6B illustrates a top view of the semiconductordevice 600 shown in FIG. 6A without the encapsulant body 660 toillustrate inner portions of the semiconductor device 600 which may beotherwise covered by the encapsulant body 660.

The semiconductor device 600 may be substantially similar to thesemiconductor device 500 but may differ at least in that the die attachpad 610 of the semiconductor device 600 may comprise a trench 613 forreceiving the interlock bonding structure 620. The interlock bondingstructure 620 may be disposed within the trench 613. As shown in FIG. 6Aand FIG. 6B, the interlock bonding structure 620 may be completelysurrounded by or completely submerged within the adhesive material 640.Specifically, the interlock bonding structure 620 shown in theembodiment in FIG. 6A and FIG. 6B may be an interlocking wire bond 620having first and second ends submerged within the adhesive material 640.Optionally, the first and second ends of the interlocking wire bond 620may be disposed within the trench 613. The arrangement with in thetrench 613 may reduce packaging height.

FIG. 6C illustrates a perspective cut-away view of the die attach pad610 and the semiconductor die 650 of the semiconductor device 600 shownin FIG. 6A. The trench 613 may extend longitudinally below the dieattach surface 616 as well as the major surface 615 of the die attachpad 610. The semiconductor die 650 may be disposed on the die attachsurface 616 such that the semiconductor die 650 may extend over andacross the trench 613 on the die attach surface 615. As shown in FIG.6C, the trench 613 may extend longitudinally along a first direction,which may be designated as longitudinal direction (L1). Thesemiconductor die 650 may extend laterally along a second direction,which may be designated as longitudinal direction (L2), and which may besubstantially orthogonal to the first longitudinal direction (L1).

FIG. 7 illustrates a cross-sectional view of a device 700. The device700 may comprise a plurality of leads 712, 714, a die attach surface716, a plurality of die attach pads 710 a-710 c, a plurality ofsemiconductor dies 750-752, a wire bond 725, a plurality of interlockingwire bonds 720-722, and an encapsulant body 760. The plurality ofsemiconductor dies 750-752 may be disposed on the plurality of dieattach pads 710 a-710 c respectively on the die attach surface 716 asshown in FIG. 7. The die attach surface 716 may be a surface of thesemiconductor device 700 configured to receive the semiconductor dies750-752.

The plurality of semiconductor dies 750-752 may comprise a firstsemiconductor die 750, as well as first and second additionalsemiconductor dies 751, 752. The plurality of interlocking wire bonds720-722 may comprise a first interlocking wire bond 720, a secondinterlocking wire bond 721 and a third interlocking wire bond 722. Theplurality of die attach pads 710 a-710 c may comprise a first die attachpad 710 a, a second die attach pad 710 b and a third die attach pad 710c. The wire bond 725 may be configured to electrically couple the firstsemiconductor die 750 to a lead 712. The first interlocking wire bond720 may have a first end attached on the first die attach pad 710 a anda second end attached on the first additional semiconductor die 751.Similarly, the second interlocking wire bond 721 may have a first endattached on the second die attach pad 710 b and a second end attached onthe second additional semiconductor die 751. The third interlocking wirebond 722 may have a first end attached on the third die attach pad 710 cand the lead 714.

The first, second and third interlocking wire bonds 720-722 may bedifferentiated from the wire bond 725 in that the first, second andthird interlocking wire bonds 720-722 may have one end attached on oneof the plurality of die attach pads 710 a-710 c so as to establish amechanical interlock with the adhesive material 740. The arrangementshown in FIG. 7 illustrates the interlocking wire bonds 720-722 may beutilized as electrical connections to the plurality of semiconductordies 750-752. The semiconductor dies 750-752 may be electricallyconnected in series but in another embodiment, the semiconductor dies750-752 may be electrically connected in parallel. The lead 714 maycomprise an additional wire bond pad configured to receive theinterlocking wire bond 722. The lead 714 and the die attach pad 710 cmay be electrically connected.

FIG. 8A illustrates a light-emitting device 800. The light-emittingdevice 800 may comprise a die attach pad 810, an emitter 850 attached onthe die attach pad 810, a first conductive lead 812, a second conductivelead 818, a third conductive lead 814, a wire bond 825, a die attachglue 840, an interlocking wire bond 820 and encapsulant body 860. Thefirst 812, second 818 and third 814 conductive leads may be disposedadjacent to the die attach pad 810. Unlike previously presentedembodiments, the die attach pad 810 shown in FIG. 8A may comprisesubstantially insulation material. The die attach pad 810 may be aportion of the encapsulant body 860 surrounded by the second lead 818.As shown in FIG. 8A, the wire bond 825 may electrically couple theemitter 850 to the first conductive lead 812. The die attach glue 840may cover a portion of the die attach pad 810 and the emitter 850 so asto adjoin the emitter 850 and the die attach pad 810. A portion of thedie attach glue 840 may extend over, and may be in direct contact with,a portion of the second conductive lead 818.

The interlocking wire bond 820 may have a first end attached to thesecond conductive lead 818, and a second end attached to the thirdconductive lead 814. The third conductive lead 814 may comprise a wirebond pad configured to receive the second end of the interlocking wirebond 820. The first end of the interlocking wire bond 820 and a portionof the wire bond may be encapsulated within the die attach glue 840. Thesecond conductive lead 818 may comprise substantially circularconductive leads surrounding the die attach pad 810.

The encapsulant body 860 may comprise a substantially reflectivematerial. The encapsulant body 860 may comprise a lower portion 862 andan upper portion 864. A surface of the lower portion 862 may define thedie attach surface 815 configured to receive the emitter 850 and thesubstantially transparent encapsulant 870. The substantially transparentencapsulant 870 may encapsulate the wire bond 825, the emitter 850, thedie attach glue 840 and at least a portion of the die attach pad 810 andthe interlocking wire bond 820.

The interlocking wire bond 820 may be configured to provide a mechanicalinterlock with the die attach glue 840, so as to mechanically adjoin thesecond conductive lead 818 and the die attach glue 840. Thus, themechanical interlock between the interlocking wire bond 820 mayindirectly improve mechanical interlock between the second conductivelead 818 and the die attach glue 840. The lower portion 862 of theencapsulant body 860 may surround the second conductive lead 818.Similarly, the mechanical interlock between the interlocking wire bond820 and the die attach glue 840 may indirectly improve mechanicalinterlock between the die attach pad 810 and the die attach glue 840.

FIG. 8B illustrates a manufacturing process step of the light-emittingdevice 800 shown in FIG. 8A. As shown in FIG. 8B, the interlocking wirebond 820 may be formed first, electrically coupling and/or connectingthe second lead 818 and the third lead 814. Next, the die attach glue840 may be applied on the die attach surface 816. Specifically, the dieattach glue 840 may be applied on the die attach pad 810 such that thedie attach glue 840 may cover substantially the die attach pad 810 andat least a portion of the second lead 818 and the first end of theinterlocking wire bond 820. This may be followed by a die attachprocess, in which the emitter 850 is attached on the die attach pad 810and the wire bond process in which the wire bond 825 is formed. Thesecond lead 818 and the interlocking wire bond 820 may electricallyconnect the emitter 850 to an external circuit (not shown).

FIG. 9A illustrates a block diagram of a lighting system 990. Thelighting system 990 may comprise a semiconductor device 900. Thesemiconductor device 900 may be one of the devices 100, 200, 300, 400,500, 600, 700, 800 illustrated in previous embodiments. FIG. 9Billustrates a block diagram of an opto-electronic system 992. Theopto-electronic system 992 may be a fiber optics system, an encoder, aproximity sensor, an optocoupler or any other device that may include anoptical die. The semiconductor device 900 may be one of the devices 100,200, 300, 400, 500, 600, 700, 800 illustrated in previous embodiments.In other words, the device 100, 200, 300, 400, 500, 600, 700, 800illustrated in previous embodiment may form a portion of the lightingsystem 990 shown in FIG. 9A or a portion of the opto-electronic system992 shown in FIG. 9B.

FIG. 10A illustrates a method for providing a mechanical interlockbetween a die attach pad of a lead frame and a semiconductor die. FIGS.10B-D illustrate various alternative steps for the method shown in FIG.10A. Referring to FIG. 10A and FIGS. 10B-10D, the method starts withstep 1010 in which at least one end of an interlocking wire bond may bewire bonded on a portion of the lead frame such that a portion of theinterlocking wire bond is disposed adjacent to the die attach pad. Next,in step 1020 a die attach glue may be applied on the die attach padcovering at least partially the interlocking wire bond. The interlockingwire bond may have first and second ends. Optionally, the method maycomprise step 1022 in which the first and second ends of theinterlocking wire bond may be attached on the die attach pad.

Then, in step 1030 the semiconductor die may be attached on the dieattach pad. In an optional step 1032, the first and second ends of theinterlocking wire bond may be surrounded with the die attach glue.Alternatively, the method may comprise step 1034 a portion of theinterlocking wire bond between the first and second ends of theinterlocking wire bond may be surrounded with the die attach glue suchthat the first and second ends of the interlocking wire are exposedoutside the die attach glue. In step 1040, the die attach glue may becured into solid form.

Different aspects, embodiments or implementations may, but need not,yield one or more of the following advantages. For example, the shape,size various dimensions and various arrangement of the elementsillustrated in the previously presented embodiments may be advantageousfor increasing the strength of mechanical interlock between the dieattach pad and the die attach glue or the adhesive material. Inaddition, various features illustrated in the specification may bedesirable for preventing failure due to delamination of epoxy that mayresult in failure of the devices. For example, the interlock bondingstructures illustrated throughout the specification may improvereliability performance of many semiconductor devices, including but notlimited to opto-electronic devices.

Although specific embodiments of the invention have been described andillustrated herein above, the invention should not be limited to anyspecific forms or arrangements of parts so described and illustrated.Features illustrated in various embodiments may be combined in anymanner as may seem fit to a person with ordinary skill in the art. Thescope of the invention is to be defined by the claims appended heretoand their equivalents.

1. A semiconductor device, comprising: a die attach pad; a major surfacecomprising at least a surface of the die attach pad; a semiconductor diemounted on the major surface; an interlocking wire bond disposed on themajor surface, the interlocking wire bond having a first end, a secondend and a center portion interposed between the first end and the secondend; and an adhesive material configured to adjoin the semiconductor dieand the die attach pad, wherein the adhesive material covers at leastpartially the center portion of the interlocking wire bond.
 2. Thesemiconductor device of claim 1, wherein the first end and the secondend of the interlocking wire bond are distanced away from the adhesivematerial.
 3. The semiconductor device of claim 1, wherein the first endand the second end of the interlocking wire bond are submerged withinthe adhesive material.
 4. The semiconductor device of claim 1, whereinthe interlocking wire bond is distanced away from the semiconductor die.5. The semiconductor device of claim 1, wherein the first end and thesecond end of the interlocking wire bond are attached on the die attachpad.
 6. The semiconductor device of claim 1, wherein the semiconductordevice further comprising an additional interlocking wire bond having afirst end and a second end, wherein the first end of the interlockingwire bond and the first end of the additional interlocking wire bond areattached on the die attach pad side-by-side.
 7. The semiconductor deviceof claim 1, wherein the semiconductor device further comprising anadditional interlocking wire bond, and wherein the interlocking wirebond and the additional interlocking wire bond are arranged interposingthe semiconductor die on the major surface of the die attach pad.
 8. Thesemiconductor device of claim 1, wherein the semiconductor die and thedie attach pad are arranged interposing the center portion of theinterlocking wire bond.
 9. The semiconductor device of claim 8, whereina portion of the semiconductor die engages the center portion of theinterlocking wire bond.
 10. The semiconductor device of claim 1, whereinthe semiconductor device further comprises an additional wire bond padadjacent to the die attach pad, and wherein the first end of theinterlocking wire bond is attached on the die attach pad and the secondend of the interlocking wire bond is attached on the additional wirebond pad.
 11. The semiconductor device of claim 1, wherein thesemiconductor die has a height measuring from the major surface, andwherein the interlocking wire bond is disposed approximately below halfof the height measuring from the major surface.
 12. The semiconductordevice of claim 1 forms a portion of a lighting system.
 13. Thesemiconductor device of claim 1 forms a portion of an opto-electronicsystem.
 14. A device, comprising: a die attach surface; a die attach paddisposed within the die attach surface; an interlock bonding structureformed on the die attach pad; a semiconductor die configured to bemounted on the die attach surface; and a die attach glue configured toadjoin the semiconductor die and the die attach pad, wherein the dieattach glue is configured to cover the interlock bonding structure suchthat the interlock bonding structure is surrounded within the die attachglue.
 15. The device of claim 14, wherein the die attach pad furthercomprises a groove and the interlock bonding structure is disposed atleast partially within the groove.
 16. The device of claim 15, whereinthe interlock bonding structure comprises a wire bond having a firstend, and wherein the first end of the wire bond is attached on a surfacewithin the groove.
 17. The device of claim 16, wherein the wire bond hassecond end disposed outside the groove.
 18. The device of claim 14,wherein the die attach pad further comprise a trench extending below thedie attach surface, and wherein the semiconductor die extends over andacross the trench on the die attach surface, and wherein the interlockbonding structure is disposed within the trench.
 19. A light-emittingdevice, comprising: a die attach pad; an emitter mounted on the dieattach pad; a first conductive lead disposed adjacent to the die attachpad; a second conductive lead disposed adjacent to the die attach pad; awire bond electrically coupled the emitter to the first conductive lead;a die attach glue in contact with a portion of the die attach pad andthe emitter so as to adjoin the emitter and the die attach pad; aninterlocking wire bond having a first end attached to the secondconductive lead, wherein at least a portion of the wire bond issurrounded by the die attach glue; and a substantially transparentencapsulant encapsulating the wire bond, the emitter, the die attachglue and at least a portion of the die attach pad and the interlockingwire bond, wherein the interlocking wire bond is configured to provide amechanical interlock with the die attach glue so as to mechanicallyadjoin the second conductive lead and the die attach glue.
 20. Thelight-emitting device of claim 19, wherein a portion of the die attachglue extends over and in direct contact with the second conductive lead.